Here is some info. It looks like it was made in ’67. If it is working you should go for it!
http://www.americanradiohistory.com/Archive-High-Fidelity/60s/High-Fidelity-1967-11.pdf
http://www.americanradiohistory.com/Archive-High-Fidelity/60s/High-Fidelity-1967-11.pdf